TiO (sub 2)-SiO (sub 2) binary oxides of low Ti content promoted photocatalytic epoxidation of propene by molecular oxygen. By catalytic runs and UV spectra, it was revealed that the isolated tetrahedral Ti species on the TiO (sub 2)-SiO (sub 2) samples are active for the photoepoxidation of proene, while the aggregated titanium oxide species are active mainly for the side reactions.

Photocatalytic systems have the potential to promote difficult reactions and are examined in both oxidative and nonoxidative systems for methane conversion. The results suggest that the pair sites consisting of the dispersed AlO4 and TiO4 species are responsible for a high activity of the SiO2-Al2O3-TiO2 photocatalyst in this reaction.